Add sauce ingredients to the slow cooker. Stir to mix well.
Add meatballs and potatoes.
Cook HIGH 2-3 hours, LOW 4-6 hours.
Add vegetable on top and cook an additional 30 minutes or until tender.
Set Instant Pot to the high saute setting. Heat oil.
Add meatballs and brown on each side, 3-5 minutes. Remove meatballs from IP. You will probably have to brown them in batches.
Add sauce ingredients and stir to mix well. Add potatoes and meatballs. Make sure you are not over capacity.
Close and seal vent. Select manual setting and set time for 7 minutes. Quick-release pressure when cook time is completed. Add vegetables and cook an additional 3 minutes on high pressure or until tender.